How Important is a Varied Diet?

Can’t you just eat the same healthy foods every day? Technically, yes, but there is one potential downside.

Monica Reinagel, MS, LD/N, CNS,
February 7, 2012
Episode #176

Josh writes: “I eat a healthy diet, but I tend to eat the same foods over and over. For example, I eat spinach every day for lunch. I know a varied diet is supposed to be best. Can some healthy foods be bad for you if you consume them too frequently?”

Josh is right: A varied diet is usually touted as the ideal—but why? After all, the ability to choose from a wide variety of foods—no matter where we live or what time of the year it happens to be—is, to a certain extent, a modern luxury. Many of our primitive ancestors thrived on extremely limited diets that might have included just one or two protein sources, a single type of grain, and a small selection of local, seasonal fruits and vegetables.  In fact, these indigenous diets are often held up as being far superior to the modern diet.

So why all the emphasis on a varied diet?   For those who would prefer to keep it simple, couldn’t you just come up with one healthy meal plan and eat it every day? Although it’s clearly not essential, a varied diet does offer at least two advantages.

Variety Covers Your Bases

First, eating a variety of foods helps ensure that you’re covering your bases, nutritionally. Green peppers, for example are a terrific source of vitamin C but don’t offer that much in the way of vitamin A. Carrots are the other way around. The different food groups tend to feature different nutrient profiles as well. Fruits and vegetables contain lots of antioxidants, nuts and seeds supply fat-soluble nutrients, grains and legumes supply minerals, and so on. Rather than trying to memorize which foods contain which nutrients, it’s easier to just aim for a reasonable amount of variety.

Variety Keeps You Safe

Secondly, variety is an easy way to avoid over-exposure to a potential hazard.

Some healthful foods contain compounds that may pose a concern if consumed in large quantities. Albacore tuna, for example, contains small amounts of mercury. It’s unlikely to be a problem if you’re eating tuna once or twice a week. But if you’re popping open a can of tuna every single day for lunch, it could be a problem.

See also: Fish and Mercury

Raw spinach contains natural compounds called oxalates. Oxalates aren’t harmful or toxic but they do have a bad habit of binding to calcium, making it more difficult for your body to absorb this important nutrient. Eating a spinach salad a few times a week isn’t likely to pose a big problem but eating spinach every single day for lunch could potentially start to impinge on your calcium status—especially if you’re counting on the milk in your lunchtime latte as one of your primary calcium sources.

See also: Best Sources of Calcium

I don’t want to make too big a deal out of this. It’s great that you’re eating greens every day for lunch, Josh, and I wouldn’t want you to cut back on your vegetable intake. (And I’ve yet to see a case of spinach-induced calcium deficiency.) But mixing it up a bit takes that concern completely off the table. If you enjoy sautéed spinach, try sautéed Swiss chard or beet greens once in a while. If you like spinach in salads or wraps, try substituting arugula or even fresh basil leaves every once in a while.

Too Much of a Good Thing?

There are even a few situations in which you can get too much of a good thing. Brazil nuts are uniquely high in the mineral selenium, for example. Eat a handful of Brazil nuts every day and you could easily end up with a selenium overload. Eat a handful of mixed nuts every day, and there’s no such risk.

For more on symptoms of selenium overload, see my episode: Can You Get Too Many Vitamins?

The point here is not that spinach or tuna or Brazil nuts are harmful but rather that a varied diet is a simple way to avoid unintentional overexposure or dietary imbalances.

Beware the Smorgasbord Effect

There’s just one little caveat I want to mention. Variety or novelty can also lead to over-eating. Research shows that we actually feel full more quickly when eating just one thing than if we’re eating several things. Most people eat more when a meal contains lots of different dishes and courses than they do at simpler meals. And you’ve probably noticed that having a wide variety of snacks and treats on hand can lead you to eat more than you would if you only had one option.  

Use this to your advantage. When it comes to desserts or football snacks, keep the variety to a minimum. But if you want your family to eat more vegetables, try serving two or even three different vegetables with meals!

See also: How to Get More Vegetables

Image courtesy of Shutterstock